Low profile vertebral stabilization systems and methods

ABSTRACT

Skeletal stabilization systems include a base, a longitudinal member, and a retaining member. The base includes an engagement surface with a surface area that is positionable in contact with a bone to atraumatically or traumatically engage the base to the bone. The retaining member engages the base to retain the longitudinal member relative to the base so that the longitudinal member can provide a desired stabilization effect to one or more adjacent bony portions.

BACKGROUND

In certain vertebral stabilization systems it is desired to secure alongitudinal member along one or more vertebral levels of the spinalcolumn to provide stabilization to the vertebrae. Fasteners that securethe longitudinal member to the vertebrae can require significantalteration of the bone. The fasteners can also project from the boneinto the adjacent tissue in order to accommodate the components of thefastener and the longitudinal member. Fasteners can also require thehandling and placement of multiple small components to engage thelongitudinal member to the fasteners. While various vertebral andskeletal stabilization systems have been developed, a need remains forlow profile stabilization systems that facilitate and expediteengagement to the bone and engagement of the longitudinal member alongthe bone.

SUMMARY

The present invention relates to skeletal stabilization systems, andmore particularly, but not exclusively, relates to vertebralstabilization systems having a coupling member securable to a vertebralbody and a longitudinal member engaged to the coupling member. Multiplecoupling members may be employed and secured along the longitudinalmember to multiple vertebrae to stabilize one or more vertebral levels.The longitudinal member may be employed alone or in combination with oneor more other longitudinal members along the same or different levels ofthe spinal column.

One embodiment includes a vertebral stabilization system having acoupling member securable to a vertebral body. The coupling memberincludes a base and a retaining member securable to the base to couple alongitudinal member positioned along the spinal column to the couplingmember. In one embodiment, the coupling member includes an engagementsurface with an adhesive to atraumatically engage the coupling member toa vertebral body. In another embodiment, the coupling member includes adistal portion extending into the vertebral body to engage the couplingmember to a vertebral body. In other embodiments, various retainingmembers are provided to retain the longitudinal member to the couplingmembers.

Other embodiments include unique apparatus, devices, systems, andmethods to stabilize vertebral bodies. Further embodiments, forms,objects, features, advantages, aspects, and benefits of the presentapplication shall become apparent from the detailed description andfigures included herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a spinal column segment with a vertebralstabilization system positioned thereon including a longitudinal memberand coupling members shown diagrammatically.

FIG. 2A is an exploded perspective of the vertebral stabilization systemaccording to one embodiment.

FIG. 2B is a side view of the vertebral stabilization system of FIG. 2Alooking toward an end of the longitudinal member.

FIG. 2C is a top view of the vertebral stabilization system of FIG. 2A.

FIG. 2D is a section view of the vertebral stabilization system of FIG.2A along line 2D-2D.

FIG. 3A is an exploded perspective of the vertebral stabilization systemaccording to another embodiment.

FIG. 3B is a side view of the vertebral stabilization system of FIG. 3Alooking toward a length of the longitudinal member.

FIG. 3C is a top view of the vertebral stabilization system of FIG. 3A.

FIG. 3D is a side view of the vertebral stabilization system lookingorthogonally to the direction of FIG. 3B.

FIG. 4A is an exploded perspective of the vertebral stabilization systemaccording to yet another embodiment.

FIG. 4B is a side view of the vertebral stabilization system of FIG. 4Alooking toward an end of the longitudinal member.

FIG. 4C is a top view of the vertebral stabilization system of FIG. 4A.

FIG. 4D is a side view of the vertebral stabilization system lookingorthogonally to the direction of FIG. 4B.

FIG. 5A is an exploded perspective of the vertebral stabilization systemaccording to another embodiment.

FIG. 5B is a side view of the vertebral stabilization system of FIG. 5Alooking toward a length of the longitudinal member.

FIG. 5C is a top view of the vertebral stabilization system of FIG. 5A.

FIG. 5D is a side view of the vertebral stabilization system lookingorthogonally to the direction of FIG. 5B.

FIG. 6 is an exploded perspective of the vertebral stabilization systemaccording to still another embodiment.

FIG. 7A is a perspective view of the vertebral stabilization system ofFIG. 6 in a first orientation.

FIG. 7B is a perspective view of the vertebral stabilization system ofFIG. 6 in a second orientation.

FIG. 8A is an exploded perspective of the vertebral stabilization systemaccording to still another embodiment.

FIG. 8B is a top view of the vertebral stabilization system of FIG. 8A.

FIG. 8C is a cross-sectional view of the vertebral stabilization systemof FIG. 8A along line 8C-8C of FIG. 8B.

FIG. 8D is a cross-sectional view of the vertebral stabilization systemof FIG. 8A along line 8D-8D of FIG. 8B.

FIG. 9 is an exploded perspective view of the vertebral stabilizationsystem of FIG. 8A utilizing a retaining clip.

FIG. 10 is a perspective of the vertebral stabilization system accordingto still another embodiment.

FIGS. 11A and 11B are a plan view and elevation view, respectively, ofanother embodiment stabilization system.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

While the present invention can take many different forms, for thepurpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsof the described embodiments and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

FIG. 1 illustrates a spinal column segment 10 with a vertebralstabilization system 14 according to one aspect of the invention.Vertebral stabilization system 14 includes an elongated longitudinalmember 18 extending along vertebrae 12 generally in the direction of thecentral axis of the spinal column segment 10. Vertebral stabilizationsystem 14 also includes a number of coupling members 13 coupled tovertebrae 12 and longitudinal member 18 to secure longitudinal member 18to the vertebrae 12. In one embodiment, coupling members 13 areconfigured to atraumatically engage the respective vertebrae 12 tomaintain integrity of the bony tissue while providing a platform or baseto which longitudinal member 18 can be mounted. In another embodiment,coupling members 13 provide a retaining device that is mounted theretowhile allowing longitudinal member 18 to be positioned in engagementwith the respective coupling member 13. The retaining device can than bemanipulated to secure the longitudinal member 18 to the coupling member13 without necessitating the surgeon to place or engage one or moreseparate components to the coupling member 13.

Longitudinal member 18 provides a desired stabilization effect tovertebrae 12 when secured thereto. Longitudinal member 18 can be in theform of a rod, wire, cable, tether, braid, suture, link, cord, plate,chain, or other device that is elongated to extend between at least twovertebrae 12. Longitudinal member 18 can be stiff, rigid, flexible,inflexible, formable, bendable, elastic, collapsible in compression andinelastic in tension, or otherwise movable in response to stimulus toprovide a desired stabilization effect when coupled to vertebrae 12.

The vertebral stabilization system 14 can be secured to vertebrae 12 ofthe spinal column segment 10 from a posterior approach as shown. Alsocontemplated are procedures that involve in posterior-lateral, lateral,antero-lateral and anterior approaches to the spinal column.Stabilization system 14 can be secured to the anterior body portion ofthe vertebrae, or to any of the posterior elements of the vertebrae. Thespinal column segment 10 may comprise two vertebrae 12 for a singlelevel stabilization procedure or three or more vertebrae 12 inmulti-level stabilization procedures. The vertebrae 12 can be any one orcombination of the sacral, lumbar, thoracic, and cervical vertebrae ofthe spinal column. In addition, multiple longitudinal members can besecured to the vertebrae along the same vertebral levels or alongdifferent vertebral levels in the same procedure.

Referring now to FIG. 2A-2D, one embodiment of vertebral stabilizationsystem 14 includes coupling member 13 with a base 16, longitudinalmember 18, and a retaining member 20. Base 16 includes a distallyoriented engagement surface 22, a proximally opening slot 24 locatedopposite engagement surface 22, and a passage 26 extending and openingproximally from engagement surface 22 with a plurality of threads 38located therein. As used herein, the terms distal, distally, proximaland proximally are employed relative to the contemplated implantationorientation of vertebral stabilization system 14 along the spinalcolumn. The terms distal and distally refer to the direction toward thepatient and the terms proximal and proximally refer to the directiontoward the surgeon and away from the patient. Longitudinal memberextends from the respective coupling members 13 transversely to thedistal-proximal direction for positioning along the spinal column.

Engagement surface 22 is configured to engage one or more bony surfacesof the respective vertebrae 12. In the illustrated embodiment,engagement surface 22 defines a through-hole 23 in communication withpassage 26. Engagement surface 22 extends around through-hole 23 in aconcentric circular arrangement. Engagement surface 22 can be smooth, orcan be textured to enhance bonding of the adhesive to engagement surface22. In another embodiment, engagement surface 22 is concavely curved toform a recess or depression in the distally oriented engagement surface22. In other embodiments engagement surface 22 may be convexly curved,flat, angled, or include complex curvatures.

In one embodiment, base 16 is generally adhesively secured to thevertebra 12 by applying any suitable biocompatible adhesive betweenengagement surface 22 and the bony surface to be engaged. The adhesivesets to firmly engage base 16 to the bone surface of the respectivevertebral body without requiring the trauma created by penetration ofthe vertebral body with a bone penetrating fastener such as a screw,staple or spike. Such atraumatic engagement substantially preserves theintegrity of the bony tissue and simplifies attachment of the base 16since no drilling or tapping is required to accommodate any fastener. Inone procedure, the base 16 is atraumatically engaged to the bone surfaceof the vertebra without any preparation of the vertebra. In otherprocedures, tissue material can be removed from the bone surface toprovide intimate contact between the engagement surface and the bone foratraumatic engagement of the engagement surface with the bone. Forexample, a limited amount of bone or tissue material can be scraped,chiseled or otherwise removed from the vertebra to form a receiving areain or adjacent to the bone surface to accommodate the engagement surface22 and provide an intimate fit therewith. The bone surface can also betextured to enhance bonding of the adhesive thereto.

In other embodiments, base 16 may be secured to the vertebra 12 with anengagement surface 22 defining a suitable fastener arrangement thattraumatically engages the bony tissue of the vertebral body.Contemplated fastener arrangements include bone screws, pins, wires,sutures, tacks, and staples, to name a few. In still other embodiments,one or more fastener arrangements are employed in combination with anadhesive.

Slots 24 pass through the center of base 16 and extend distally from theproximal end of base 16 through its center to a location adjacent toengagement surface 22. In other embodiments slots 24 may not passthrough the center of base 16. Slots 24 define a U-shape that opensalong one of the respective opposite sides of base 16. Base 16 includesinternal threads 17 formed therealong that extend about the innersurface thereof defined by passage 26. Internal threads 17 extendbetween the opposite slots 24. Slots 24 are sized to accommodate thesize and shape of longitudinal member 18 in close fit with one another.

Retaining member 20 includes an outer thread profile 38, an instrumentengaging portion 30, and a distally oriented longitudinal memberengaging surface 32. The instrument engaging portion 30 is a hexagonallyshaped recess, but may include other shapes to non-rotatably engage adriving instrument. In another form, engaging portion 30 is a stem aboutwhich a socket or wrench is positioned. Thread profile 38 is configuredto engage the internal threads 17 in passage 26 of base 16. As theretaining member 20 is rotated with respect to the base 16, the distallongitudinal member engaging surface 32 urges the longitudinal member 18against the bottom of the slots 24 to secure the longitudinal member 18therewithin.

In use during one spinal stabilization procedure, the spinal columnsegment 10 is accessed from a desired approach for implantation ofstabilization system 14. One base 16 is adhesively secured to one of therespective vertebrae 12, and the procedure is repeated for one or moreadditional vertebrae 12. Longitudinal member 18 is inserted into theslots 24 of each of the bases 16. Longitudinal member 18 may be bent,flexed or deformed for positioning into the slots 24 if so configured.Retaining members 20 are threadingly engaged into the passages ofrespective ones of the bases 16 to retain longitudinal member 18 in base16. In one embodiment, retaining member 20 is positioned againstlongitudinal member 18 to urge it against the bottom of the slots 24 andfixedly engage longitudinal member 18 to base 16. In another embodiment,longitudinal member 18 is retained in slots 24 but permitted to float oraxially translate in slots 24.

Referring now to FIGS. 3A-3D, another embodiment of vertebralstabilization system 14 is designated as system 114 and includes atleast one coupling member 113 for securing longitudinal member 18 alongthe spinal column. Coupling member 113 includes a base 116 and aretaining member 120. Base 116 includes a distally oriented engagementsurface 122 formed along a distal foot 121 and a post 125 extendingproximally from foot 121. Post 125 includes a distal slot 124 locatedproximally of foot 121, and a passage 126 extending proximally from slot124. Post 125 includes a thread profile 128 located on the outer surfacethereof and a central opening 134 at the proximal end thereof that is incommunication with passage 126.

Engagement surface 122 can receive an adhesive to secure it to a bonesurface of the vertebra 12. Engagement surface 122 is flat in theillustrated embodiment and includes a square or rectangular footprint toincrease the contact area with the bone surface. Other embodimentscontemplate other configurations as discussed above with respect toengagement surface 22.

Slot 124 extends through post 125, and post 125 is solid around opening134 between passage 126 and the proximal end of post 125 so that passage126 is completely encircled by post 125. Slot 124 is located adjacent adistal end of post 125 adjacent foot 121. Passage 126 is enlargedrelative to slot 124, and provides a distally tapered transition to slot124 to facilitate centering of longitudinal member 18 into slot 124. Thebottom of slot 124 is generally shaped to accommodate the size and shapeof longitudinal member 18.

Retaining member 120 includes a cap 132 with a smooth, outer surface 136that has a distal cylindrical portion and a proximally taperedfrusto-conical shape extending from the distal cylindrical portion alongwith an internal thread profile 138. A proximal opening 140 is providedto receive a driving instrument. Other embodiments contemplate otherarrangements for engaging a driving instrument as discussed above withrespect to retaining member 20. Retaining member 120 also includes adistal longitudinal member engaging surface 142. Thread profile 138 isconfigured to threadingly engage thread profile 128 along post 125.

Longitudinal member 18 is inserted in an end-wise manner through passage126 of post 125 of each of the coupling members 113 of the stabilizationsystem. Passage 126 can be elongated in the proximal and distaldirections to facilitate placement of longitudinal member 18therethrough. As retaining member 120 is rotated to engage post 125,longitudinal member engaging surface 142 contacts and urges longitudinalmember 18 along passage 126 and into slot 124 against the bottom of slot124 to secure longitudinal member 18 within slot 124 against foot 121.As shown in FIGS. 3B and 3D, longitudinal member 18 can be clamped atits contact locations with surface 142 to prevent any movement oflongitudinal member 18 relative to coupling member 113. Two such clampedlocations are provided where longitudinal member 18 exits slot 124 onopposite sides of post 125. Other embodiments contemplate arrangementsbetween coupling member 113 and longitudinal member 18 wherelongitudinal member 18 is maintained, retained or restricted in couplingmember 113 with retaining member 120.

Referring now to FIGS. 4A-4D, another embodiment of vertebralstabilization system 14 is designated as system 214. Stabilizationsystem 214 includes at least one coupling member 213 for securinglongitudinal member 18 along the spinal column. Coupling member 213includes a base 216 and, like coupling member 13 discussed above,retaining member 20. Base 216 includes a distal foot 221 having a distalengagement surface 222. A post 225 extends proximally from foot 221, andincludes a pair of semi-cylindrical arms 227, 229 that form a proximallyopening passage 226 therebetween. Arms 227, 229 are spaced from oneanother with opposite slots 224. Slots 224 can be tapered distally sothat a distal end thereof adjacent foot 221 is sized and shaped toreceive longitudinal member 18 in a close fit while the proximalportions of slots 224 are enlarged to facilitate placement oflongitudinal member 18 into slots 224.

Engagement surface 222 can receive an adhesive to secure it to a bonesurface of the vertebra 12. Engagement surface 222 is flat in theillustrated embodiment and includes a square or rectangular footprint toincrease the contact area with the bone surface. Other embodimentscontemplate other configurations as discussed above with respect toengagement surface 22.

Arms 227, 229 include a thread profile 228 in the concavely curved sidethereof that extends along passage 226. Arms 227, 229 also includetransverse receptacles 234 to receive a portion of an insertion andplacement instrument, facilitating the grasping of base 216 with suchinstruments so it can be positioned into the patient during surgery.When longitudinal member 18 is positioned in passage 226, retainingmember 20 is engaged into the proximal opening of passage 226 to arms227, 229. Retaining member 20 is threaded along arms 227, 229 to movelongitudinal member 18 distally along slots 224 to seat in the distalend thereof adjacent foot 221. Retaining member 20 can apply sufficienttorque to clamp longitudinal member 18 at the sides of retaining member20 opposite of instrument engaging portion 30. Other embodimentscontemplate non-clamped engagement of longitudinal member 18 in couplingmember 213.

Referring now to FIGS. 5A-5D, another embodiment of vertebralstabilization system 14 is designated as system 314. System 314 includesat least one coupling member 313 and longitudinal member 18. Couplingmember 313 includes a base 316 and a retaining member 320 that ispositionable about and rotatable relative to base 316.

Base 316 includes a distal engagement surface 322 that is securable tothe bone surface of the vertebra 12 with an adhesive. Engagement surface322 is flat and circular in shape in the illustrated embodiment. Otherembodiments contemplate other shapes and forms for engagement surface322 as discussed above with respect to engagement surface 22.

Base 316 includes a distal slot 324 extending therein from the proximalside thereof. Slot 324 includes an enlarged central portion 323. Base316 further includes opposite outwardly extending engaging members 326a, 326 b that are in the form of cylindrical pins in the illustratedembodiment.

Retaining member 320 is in the form of a cylindrical disc with adistally opening passage 330 that is sized to extend around the outerperimeter of base 316. Retaining member 320 includes proximal opening332 formed in proximal end wall 334 and sidewall 336 extending distallyfrom end wall 334 around passage 330. Retaining member 320 also includesa proximal slot 342 extending across proximal end wall 334 and intosidewall 336. Transverse slots 340 a and 340 b extend from respectiveends of proximal slot 342 around a portion of the perimeter of sidewall336. Transverse slots 340 a, 340 b and proximal slot 342 divide sidewall336 to form opposite fingers 348 a, 348 b extending along slots 340 a,340 b, respectively. Proximal opening 332 can facilitate placement of aninstrument to engage longitudinal member 18 in slot 324, or to receive abead or other structure extending about longitudinal member 18. Proximalopening 332 can receive an instrument that rotates retaining member 320to secure it to base 316. Proximal opening 332 can also provide anarrangement with slots 342 that allows a counter-torque to be engaged tobase 316 while an instrument in slots 342 rotates retaining member 320.

With retaining member 320 assembled to base 316, coupling member 313 issecured to the vertebral body. Retaining member 320 is positioned onbase 316 in a first orientation so that proximal slot 342 of retainingmember 320 is aligned with distal slot 324 of base 316, as indicated bythe dashed lines of FIG. 5C. In this orientation, engaging members 326a, 326 b are located in transverse slots 340 a, 340 b adjacent proximalslot 342. Longitudinal member 18 can be positioned through proximal slot342 and into distal slot 324 until aligned or generally aligned withtransverse slots 340 a, 340 b. Retaining member 320 is then rotated to asecond orientation where engaging members 326 a, 326 b are locatedadjacent the ends of slots 340 a, 340 b remote from proximal slot 342.In the second orientation, longitudinal member 18 is located intransverse slots 340 a, 340 b and proximal slot 342 extends obliquely tolongitudinal member 318, as best shown in FIG. 5C. In the secondorientation, fingers 348 a, 348 b of sidewall 336 capture longitudinalmember 18 in slot 324, and engaging members 326 a, 326 b engage sidewall336 to prevent retaining member 320 from being removed from base 316.

As best shown in FIG. 5D, sidewall 336 includes a projection 344 alongand extending into each of the transverse slots 340 a, 340 b from therespective finger 348 a, 248 b. The projection maintains retainingmember 320 in the second orientation to prevent it from rotatingrelative to base 316 and secured the respective engaging member 326 a,326 b adjacent the blind end of the respective transverse slot 340 a,340 b. Fingers 348 a, 348 b can flex above the respective adjacenttransverse slot 340 a, 340 b to allow passage, if needed, of theprojection 344 over longitudinal member 18 upon application ofsufficient force. Fingers 348 a, 348 b of sidewall 336 also include asecond projection 346 adjacent proximal slot 342 to form a recess 345 toreceive the respective adjacent engaging member 326 a, 326 b andmaintain retaining member 320 in the first orientation relative to base316.

In the second orientation, longitudinal member 18 is positioned intransverse slots 340 a, 340 b and is captured therein by fingers 348 a,348 b of sidewall 336. Longitudinal member 18 is spaced from sidewall336 in slots 340 a, 340 b so that longitudinal member 18 can move atleast longitudinally relative to coupling member 313. In this condition,spinal motion of the stabilized vertebral levels remains is permitted,but is restrained in rotation and lateral extension by tensioning oflongitudinal member 18. Other arrangements contemplate an engagementrelationship where longitudinal member 18 is constrained relative tocoupling member 313. For example, sidewall 336 can contact longitudinalmember 18 to restrict longitudinal movement of longitudinal member 18relative to coupling member 313. In other forms, a set screw, crimp orother device can be engaged to or in retaining member 320 and withlongitudinal member 18 to secure it within base 316.

Referring now to FIG. 6, another embodiment of stabilization system 14is shown and designated as stabilization system 414 with a couplingmember 413 and longitudinal member 18. Coupling member 413 includes abase 416 and a retaining member 420. Base 416 includes a cylindricaldisc shape with a distal engagement surface 422 and a proximallyoriented slot 424 opposite engagement surface 422. Distal engagementsurface 422 is securable to the bone surface of the vertebra 12 with anadhesive. Engagement surface 422 is flat and circular in shape in theillustrated embodiment. Other embodiments contemplate other shapes andforms for engagement surface 422 as discussed above with respect toengagement surface 22.

The proximal side of base 416 includes engagement recesses 426 a, 426 bon opposite sides thereof that are in communication with slot 424. Eachengagement recess 426 a, 426 b includes an enlarged portion 428 having asemi-circular shape adjacent slot 424 and an outer portion 432 adjacentthe outer perimeter of base 416. Outer portion 432 includes a groovedportion 434 extending thereabout. Outer portion 432 is connected toenlarged portion 428 with a neck portion 430.

Retaining member 420 is engageable to longitudinal member 18 and to base416 to secure longitudinal member 18 to base 416. Retaining member 420includes receiving portions 440, 442 that have a semi-cylindrical shapeand form a receiving passage 441, 443, respectively, to receivelongitudinal member 18 therein. Receiving portions 440, 442 are linkedby a connecting arm 446 having a semi-circular shape. An engaging member448 extends from connecting arm 446 opposite receiving portions 440,442. Engaging member 448 includes a pair of legs 450, 452 separated by acentral slot 454. Slot 454 allows legs 450, 452 to resiliently flextoward one another in response to compression forces moving the legs450, 452 toward one another.

FIGS. 7A and 7B show retaining member 420 configured to securelongitudinal member 18 to base 416. In FIG. 7A retaining member 420 ispositioned with engaging member 448 in outer portion 432 of engagementrecess 426 b. Legs 450, 452 are slightly compressed toward one anotherand reside in grooved portion 434 to secure retaining member 420 to base416. Engaging member 448 extends through neck portion 430 and connectingarm 446 is located in enlarged portion 428 of engagement recess 426 b.Receiving portions 440, 442 are oriented so that receiving passages 441,443 are oriented distally in slot 424 of base 416 and positioned aroundlongitudinal member 18. Receiving portions 440, 442 frictionally engagethe sides of slot 424 to resist displacement of receiving portions 440,442 from slot 424. Retaining member 420 captures longitudinal member 18in slot 424 and maintains it in engagement with base 416. In oneprocedure, longitudinal member 18 is positioned in or adjacent slot 424,and retaining member 420 is positioned so that receiving portions 440,442 are located around longitudinal member 18 and engaging member 448engages engagement recess 426 b. Receiving portions 440, 442 are, ifnecessary, then positioned into slot 424. Alternatively, retainingmember 420 can be oriented to engage base 416 in engagement recess 426 awith passages 441, 443 opening distally into slot 424.

FIG. 7B is similar to FIG. 7A except retaining member 420 is positionedwith passages 441, 443 of receiving portions 440, 442 orientedproximally and engaging member 448 is secured in engagement recess 426a. In this configuration, longitudinal member 18 can be press fit intoreceiving portions 440, 442 either before or after retaining member 420is engaged to base 416. Alternatively, retaining member 420 can beoriented to engage base 416 in engagement recess 426 b with receivingportions 440, 442 oriented to open passages 441, 443 proximally in slot424. In either orientation, longitudinal member 18 is configured to bepress fit into receiving portions 440, 442 to maintain it in engagementwith base 416.

In another procedure, base 416 of coupling member 413 is secured to thebony surface of a vertebra. Retaining member 420 is secured to base 416in the orientation of FIG. 7B either before or after engagement of base416 to the vertebra. Longitudinal member 18 is positioned into theproximally opening receiving portions 440, 442. Retaining member 420 isthen released from engagement recess 426 a and rotated to the positionof FIG. 7A so that engaging member 448 engages engagement recess 426 band receiving portions 440, 442 are oriented so that passages 441, 443open distally toward base 416. Longitudinal member 18 is capturedbetween base 416 and retaining member 420. Receiving portions 440, 442can frictionally engage longitudinal member 18 to prevent or restrictlongitudinal movement of member 18 relative to base 416. In anotherembodiment, longitudinal member 18 is sized relative to receivingpassages 441, 443 to allow longitudinal movement longitudinal member 18relative to coupling member 413.

Referring now to FIGS. 8A-8D, another embodiment of vertebralstabilization system 14 is designated as stabilization system 514.Stabilization system 514 includes a coupling member 513 and longitudinalmember 18 secured to coupling member 513 to provide stabilization alonga spinal column segment when coupling member 513 is secured to avertebra. Coupling member 513 includes retaining element 420 like thatdiscussed above with respect to FIGS. 6 and 7A-7B. Coupling member 513also includes base 516 that has a base portion 522 and a saddle portion540. Saddle portion 540 includes a mounting member 542 that is pivotallymounted to base portion 522 to allow pivoting movement of saddle portion540 relative to base portion 522.

Saddle portion 540 is similar to base 416 discussed above, but includesmounting member 542 extending distally therefrom rather than a distalengagement surface. Otherwise, saddle portion 540 includes a proximallyoriented slot 544 to receive longitudinal member 18, and oppositeengaging recesses 546 a, 546 b to receiving retaining element 420 in themanner discussed above with respect to base 416 of coupling member 413.

Base portion 522 includes a distally oriented engagement surface 524that is positionable in contact with the bony surface of a vertebralbody. Engagement surface 524 can be secured with an adhesive to the bonysurface as discussed above with respect to engagement surface 22. Otherembodiments contemplate other forms for engagement surface 524 asdiscussed above with respect to engagement surface 22.

Base portion 522 further includes a proximally opening socket 526centered therein in a dome-shaped proximal surface 528. Base portion 522further includes a side-opening lead-in passage 530 in surface 528 thatis in communication with socket 526. Deformation passages 532 a, 532 bextend orthogonally to lead-in passage 530 and include blind endsadjacent thereto at a location offset from socket 526, as best shown inFIG. 8C.

Saddle portion 540 is assembled with base portion 522 by positioningmounting member 542 in lead-in passage 530 and moving mounting membertherealong and into socket 526. Mounting member 542 includes a sphericalshape and is axially restrained in socket 526 at neck portion 527 ofsocket 526 as best shown in FIG. 8D. To prevent mounting member 542 fromdisplacing back through lead-in passage 530, base portion 522 can bedeformed by placing pliers, forceps or other squeezing type instrumentin deformation passages 532 a, 532 b and deforming the material of baseportion 522 to reduce the size of at least a portion of lead-in passage530 to retain mounting member 542 in socket 526. Mounting member 542retains its pivotal movement capability in socket 526 so that saddleportion 540 is pivotal relative to base portion 522.

In another embodiment shown in FIG. 9, stabilization system 514′ issimilar to stabilization system 514, but includes an alternate means forsecuring mounting member 542 in socket 526. Base portion 522′ of base516′ does not include deformation passages, although providing the sameis not precluded. Base portion 522′ includes a lead-in passage 530′ thatincludes a groove 531 formed therein to receiving a retention member554. Retention member 554 is in the form of a C-shaped clip that ispositioned in groove 531 to block lead-in passage 530′ at socket 526,and prevent mounting member 542 from backing out of socket 526 afterinsertion therein from lead-in passage 530′.

In either of the embodiments for stabilization systems 514 and 514′ thesaddle portion is pivotal relative to the base portion so that the baseto which the longitudinal member is coupled can pivot to permit at leastsome range of spinal motion while providing stabilization andlimitations to the spinal motion of the stabilized vertebral levels. Thepivoting arrangement of the saddle portion relative to the base portioncan also facilitate assembly of the spinal stabilization system sincecoupling members can be manipulated to align the receiving slot in adesired orientation suited to receive the longitudinal member. It iscontemplated that stabilization systems can be assembled that includemultiple coupling members 513, 513′ having pivoting capabilities, eitheralone or in combination with one or more of the other coupling members13, 113, 213, 313, 413 disclosed herein that do not providing pivotingcapability.

Referring now to FIG. 10, there is shown another embodiment of vertebralstabilization system 14 designated as vertebral stabilization system614. System 614 includes a coupling member 613 with a base 616 andretaining member 420 secured to base 616 to couple longitudinal member18 to base 616. Base 616 includes a distal engagement portion 618 with athread profile 620 extending therealong to threadingly engage a bonystructure such as a vertebra 12. Base 616 also includes a proximalportion 622 that includes proximally extending slot 624 and engagementrecesses 626 a, 626 b to engage retaining member 420. Proximal portion622 can be configured like the proximally oriented portion of base 416discussed above to secure retaining member 420 thereto.

In another embodiment, proximal portion 622 can be configured like base316 discussed above and a retaining member like retaining member 320 isprovided for engagement thereto. In another embodiment, proximal portion622 can be configured like base 216 or base 16 discussed above and aretaining member like retaining member 20 is provided for engagementthereto. In yet another embodiment, proximal portion 622 can beconfigured like base 116 discussed above and a retaining member likeretaining member 120 is provided for engagement thereto.

FIGS. 11A and 11B show another embodiment stabilization system 714 thatincludes a plurality of coupling members 413 spaced along anotherembodiment longitudinal member 718. Longitudinal member 718 includes aflexible portion 720 that is secured to bases 416 with the respectiveretaining members 420 as discussed above. Longitudinal member 718 alsoincludes a rigid leader portion 724 at one end thereof to facilitateinsertion of longitudinal member 718 through the bases, retainingmembers and/or crimps.

Stabilization system 714 further includes a plurality of internal crimps730 that are securely engaged to longitudinal member 718 in the centralspace formed between receiving portions 440, 442 of the respectiveretaining members 420. Internal crimps 730 include a central passage toreceive longitudinal member 718 and opposite portions 732, 734 that aresqueezed or crimped together to engage longitudinal member 718 in thecentral passage. Internal crimps 730 contact at least one of retainingmember 420 and base 416 to prevent longitudinal member 718 from movingaxially relative to the respective coupling member 413. While each ofthe coupling members 413 is shown with an internal crimp 730, it iscontemplated that fewer than all the coupling members 413 or none of thecoupling members 413 can be provided with an internal crimp 730.

In addition to or in lieu of internal crimps 730, longitudinal member718 is provided with an external crimp 728 positioned therealong outsideof and adjacent to one or both of the coupling members 413 at theopposite ends of longitudinal member 718. In other embodiments, externalcrimps 728 are positioned along longitudinal member 718 between couplingmembers 413. External crimp 728 includes a central passage to receivelongitudinal member 728 and an outer wall 729 that is deformable tocrimp or engage longitudinal member 718 in the passage. External crimp728 can abut the adjacent coupling member 413 to maintain a tension orrelative positioning the longitudinal member 718 relative to thecoupling members 413. In lieu of an external crimp 728, one of the endsof longitudinal member 718 can be provided with an enlarged retainingportion 726 formed integrally or pre-attached therewith at the end oflongitudinal member 718. Retaining portion 726 abuts or is positionedadjacent to the respective coupling member 413, and acts with theexternal crimp 728 to maintain compression or limit displacement of thevertebral levels along which longitudinal member 718 is engaged.

In one procedure, longitudinal member 718 is positioned along thecoupling members 413 with retaining member 726 adjacent the mostcephalad or most caudal coupling member 413, and external crimp 728 ismoved along longitudinal member 718 to a location adjacent the other ofthe most cephalad and caudal coupling members 413. When the desiredtension and positioning of longitudinal member 718 has been achieved,external crimp 728 is engaged to longitudinal member 718 to maintain thetension and positioning of longitudinal member 718 relative to thecoupling members 413. Alternatively or additionally, internal crimps 730can be engaged to longitudinal member 718 in the respective couplingmembers 413 to maintain the axial positioning and tensioning oflongitudinal member 718 relative to the respective coupling member 413.In still other embodiments, longitudinal member 718 and crimps 728, 730are employed with any one or combination of the coupling memberembodiments discussed herein.

Crimps 728, 730 can be engaged to longitudinal member 718 prior todelivery of longitudinal member 718 to the implantation location. Inother embodiments, internal crimps 730 are not engage tightly tolongitudinal member 718, and are allowed to translate along longitudinalmember 718 in response to spinal motion. Longitudinal member 718 canwork in conjunction with the coupling members to provide a tension bandsto allow vertebral load sharing but restrict motion by tensioning tolimit vertebral displacement.

The stabilization systems can employ a number of identical couplingmembers to secure the longitudinal member 18 to the vertebrae 12. Otherembodiments contemplate systems employing various combinations of typesof coupling members. For example, the coupling members at the cephaladand caudal ends of the longitudinal member can be configured to crimp orotherwise fixedly retain the longitudinal, member therein, while one ormore intermediate coupling members can be configured to permit axialtranslation of the longitudinal member, or to provide a pivotingplatform to which the longitudinal member is engaged.

The longitudinal member can be rigid such as with a metal spinal rod orflexible like a cable or tether. The longitudinal member can be madefrom any suitable biocompatible material, including titanium andtitanium alloys, nickel-titanium alloys, superelastic materials, shapememory materials, stainless steel and stainless steel alloys, polymersor polymeric material such as polyetheretherketone, fabrics, polyesters,or elastomers, for example. The longitudinal member can include anycross-sectional profile, including round, oval, square, rectangular,polygonal or irregular cross-sections. The longitudinal member canprovide stiffness to resist axial compression loading, or can becollapsible under compression loading resulting from spinal loads. Thelongitudinal member can be tensioned and then secured between respectiveones of the coupling members so that when the tension is released thelongitudinal member is pre-stressed to apply a compression loadingbetween the stabilized vertebral level or levels. The longitudinalmembers can be provided in pre-set lengths, or can be cut to a desiredlength before or after implantation.

Any theory, mechanism of operation, proof, or finding stated herein ismeant to further enhance understanding of the present invention and isnot intended to make the present invention in any way dependent uponsuch theory, mechanism of operation, proof, or finding. It should beunderstood that while the use of the word preferable, preferably orpreferred in the description above indicates that the feature sodescribed may be more desirable, it nonetheless may not be necessary andembodiments lacking the same may be contemplated as within the scope ofthe invention, that scope being defined by the claims that follow. Inreading the claims it is intended that when words such as “a,” “an,” “atleast one,” “at least a portion” are used there is no intention to limitthe claim to only one item unless specifically stated to the contrary inthe claim. Further, when the language “at least a portion” and/or “aportion” is used the item may include a portion and/or the entire itemunless specifically stated to the contrary. While the invention has beenillustrated and described in detail in the drawings and foregoingdescription, the same is to be considered as illustrative and notrestrictive in character, it being understood that only the selectedembodiments have been shown and described and that all changes,modifications and equivalents that come within the spirit of theinvention as defined herein or by any of the following claims aredesired to be protected.

1. A vertebral stabilization system, comprising: a base including adistal foot and a proximal engagement structure extending proximallyfrom said distal foot, wherein said distal foot includes an engagementsurface projecting laterally outwardly from said engagement structureand said engagement surface includes a surface area positionable towarda vertebral body, wherein said engagement surface includes abiocompatible adhesive on said surface area that is configured toatraumatically engage said base to the vertebral body, wherein said baseincludes a pair of arms extending away from said engagement surface,said pair of arms defining first and second proximally oriented slotsbetween said pair of arms extending in a first direction along said baseand said pair of arms define a passage in communication with said firstand second slots, said pair of arms defining an internal thread profilethat extends around said passage, wherein said passage includes anenlarged portion between said pair of anus that extends distally from aproximal opening of said passage and said first and second slots taperdistally from said enlarged portion to distal ends of said first andsecond slots, said first and second slots forming openings through saidbase at opposite sides of said base; a longitudinal member positionedthrough said openings formed by said first and second slots andextending from said base in said first direction and each of said firstand second slots taper distally on opposite sides of said longitudinalmember so that said longitudinal member intimately fits in said distalends of said first and second slots; and a retaining member positionedbetween said first and second slots and threadingly engaged to saidinternal thread profile in contact with said longitudinal member tosecure said longitudinal member against said base in said first andsecond slots.
 2. The system of claim 1, wherein: said retaining memberis engaged between said arms in said passage in contact with saidlongitudinal member to engage said longitudinal member against said basein said slot.
 3. The system of claim 2, wherein said passage extendsthrough said engagement surface so that said engagement surface extendsaround said passage.
 4. The system of claim 2, wherein said engagementsurface is defined along a distal surface of said distal foot, and saidpair of arms extend proximally from said distal foot.
 5. The system ofclaim 4, wherein said distal foot and said engagement surface definesaid surface area with a polygonal shape, and said pair of arms eachdefine a semi-cylindrical shape extending from said distal foot withconcavely curved surfaces oriented toward one another, wherein said slotand said passage are located between said pair of arms.
 6. A vertebralstabilization system, comprising: a base including a distal footengageable with a vertebral body, a pair of arms extending proximallyfrom said foot, said pair of arms defining a proximally opening passagetherebetween and first and second slots between said pair of arms, saidfirst and second slots extending on a proximal side of said footdistally of said passage, said first and second slots forming openingsthrough said base on opposite sides of said base, said passage includingan enlarged portion between said pair of arms that extends distally fromsaid proximal opening with said first and second slots tapering distallyfrom said enlarged portion to a distal end of each of said first andsecond slots, wherein said distal foot defines a planar distalengagement surface positionable toward the vertebral body and furthercomprising a biocompatible adhesive on said engagement surfaceconfigured to atraumatically engage said base to the vertebral body; alongitudinal member positioned in said first and second slots andextending from said base through said openings in a transverseorientation to said pair of arms, wherein said first and second slotstaper distally on opposite sides of said longitudinal member so thatsaid longitudinal member intimately fits in said distal ends of saidtapered first and second slots and said first and second slots enlargefrom said distal end thereof to said enlarged portion of said passage;and a retaining member engaged in said passage between said pair of armsto secure said longitudinal member in said first and second slots ofsaid base, wherein said retaining member is positioned between saidfirst and second slots.
 7. The system of claim 6, wherein said distalfoot and said planar distal engagement surface project laterallyoutwardly from said pair of arms.
 8. The system of claim 6, wherein saidfoot defines said distal engagement surface with a polygonal shape andeach of said pair of anus includes a semi-cylindrical shape with concaveportions oriented toward one another.
 9. The system of claim 6, whereinsaid passage extends through said foot and opens distally.
 10. Thesystem of claim 6, wherein said pair of arms define an internal threadprofile that extends around said passage and between said openings ofsaid first and second slots and said retaining member is threadinglyengaged to said internal thread profile in contact with saidlongitudinal member to secure said longitudinal member in said first andsecond slots.